Venus Williams out at U.S. Open

China's Li Na reacts to an instant replay of a shot against Sofia Arvidsson, of Sweden, during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Kathy Willens)

Mikhail Youzhny, of Russia, reacts during a first round match to Nicolas Mahut, of France, during the first round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Mike Groll)

Agnieszka Radwanska, of Poland, reacts during her second round match against Maria-Teresa Torro-Flor, of Spain, during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Kathy Kmonicek)

Venus Williams reacts during a second round match against Jie Zheng, of China, at the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Kathy Kmonicek)

Mikhail Youzhny wipes sweat from his face during a first round match against Nicolas Manhut at the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Mike Groll)

Andy Murray, of Britain, chases down a return against Michael Llodra, of France, during the first round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. Murray defeated Llodra. (AP Photo/Charles Krupa)

Li Na, of China, returns a shot against Sofia Arvidsson, of Sweden, during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Kathy Willens)

Jie Zheng of China reacts after beating Venus Williams in three sets during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Kathy Kmonicek)

Venus Williams falls to the court as she misses a shot against Jie Zheng of China in a tie breaker during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Darron Cummings)

Venus Williams returns a shot to Jie Zheng, of China, during the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Kathy Kmonicek)

Sloane Stephens, of the United States, cradles the ball as she prepares to serve to Urszula Radwanska of Poland, during the second round of the 2013 U.S. Open tennis tournament, early Thursday, Aug. 29, 2013, in New York. (AP Photo/Charles Krupa)

Urszula Radwanska, of Poland, returns to Sloane Stephens, of the United States, during the second round of the 2013 U.S. Open tennis tournament, early Thursday, Aug. 29, 2013, in New York. (AP Photo/Charles Krupa)

Sloane Stephens, of the United States, wipes her brow in her match to Urszula Radwanska, of Poland, during the second round of the 2013 U.S. Open tennis tournament, early Thursday, Aug. 29, 2013, in New York. (AP Photo/Charles Krupa)

James Blake returns a shot to Ivo Karlovic, of Croatia, during a first round match at the U.S. Open tennis tournament Wednesday, Aug. 28, 2013, in New York. (AP Photo/Darron Cummings)

Ivo Karlovic, of Croatia, returns a shot to James Blake

Andy Murray, of Britain, pumps his fist after winning a point against Michael Llodra, of France, during the first round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Charles Krupa)

Michael Llodra, of France, follows through on a return between his legs against Andy Murray, of Britain, in the first round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. (AP Photo/Charles Krupa)